Pakistani authorities say an estimated 200 militants crossed the border from Afghanistan and attacked a Pakistani border post starting a lengthy battle that has left at least 27 security troops and three civilians dead. Pakistani officials say more than 35 of the militants were also killed.

The clash in the Dir tribal area of Pakistan began Wednesday and lasted well over 24 hours, although Pakistani officials say the area had calmed by midday Thursday, with Pakistani forces regaining control of the area.

The location borders Afghanistan's Kunar province and has been a center for al-Qaida and other militants in the past.

U.S. and NATO officials have long complained that insurgent fighters in Pakistan's northwest tribal region have launched attacks against their troops in neighboring Afghanistan.

But Pakistani Military Spokesman Athar Abbas says the border region is equally a problem for Pakistan, as militants based in Afghanistan are able to attack Pakistani border positions while Pakistani forces are engaged elsewhere.

"There is an active military operation that is going against the militants; and the problem of cross border movement, the problem of porous border, the problem of sanctuaries which is given in Kunar Province in Afghanistan, the militants are attacking our troops and posts from Kunar province," said Abbas. "So, we are trying to handle this. We are trying to stabilize the situation."

Pakistan has been under increased scrutiny and pressure to go after Taliban and al-Qaida militants, following the May 2 raid that killed al-Qaida leader Osama Bin Laden in the Pakistani city of Abbottabad, near the country’s capital.

And the attack on the border post comes amid media reports the United States has been pressing Pakistan to attack extremist safe havens in the North Waziristan tribal region.

But the head of Pakistan’s military in the region, Lieutenant General Asif Yasin Malik says the military has no plans to launch an offensive in North Waziristan. Malik says his forces are already stretched thin and need to consolidate their gains before moving on to other areas.

"As a military commander I would like to stabilize the areas which are still sort of violent or unstable and then be in a position to go to North Waziristan or wherever I am tasked to," said Malik. "I cannot undertake multiple operations at the same time."

The general described the situation in North Waziristan as "calm" and said he has more than 30,000 troops in the region.